US Publication No. 2009/0151738, incorporated herein by reference, teaches that a degradable cigarette filter is obtained by contacting the cellulose acetate cigarette tow with, in one embodiment, a mixture of a water soluble matrix material and a combination of a weak organic acid and a compound that can be hydrolyzed to a strong acid.
The compounds that can be hydrolyzed to a strong acid are identified as: cellulose sulfate, dodecyl sulfate, ascobryl-2-sulfate, ascorbyl-2-phosphate, phosphorus pentoxide, phosphorus pentoxide based esters, cellulose nitrate, 2-ethyl hexyl phosphate, and combinations thereof. These compounds are esters of strong acids and many are unstable (meaning that they will decompose in a relatively short period of time and thereby making them unuseable in many applications). Therefore, these esters are typically provided commercially as a salt of the ester. These ester salts are stable and do not degrade over time like their non-salt versions. However, their stability inhibits their use in the instant application.
Accordingly, the foregoing compounds that can be hydrolyzed to strong acids must be modified to make them work more aggressively (i.e., hydrolyze into strong acids which in turn catalyze the degradation of the cellulose acetate) in the instant application.